A comparison of Numeric Pain Rating Scale (NPRS) and the Visual Analog Scale (VAS) in patients with chronic cancer-associated pain.

217 Background: Though numerical rating scales (NRS) are frequently used, a subset of patients do not understand the abstract nature on NRS and use quality descriptors of severity. We used a visual analog scale (VAS) using descriptors of “good day”, “average day” and “bad day” along a 10-cm line and compared it to a NRS in patients with cancer diagnosis and pain 1 month or longer. Methods: Eligible patients were verbally consented and completed the two scales. We asked patients thoughts about which they felt was the more appropriate scale to gauge their pain. The scales were compared by the distance from the extreme left of the line to the mark the patient placed on the VAS. Additional data included demographic and diagnosis information. The VAS and NRS were compared using two-sample t-tests or Wilcoxon rank-sum tests and Pearson’s chi-square or Fisher’s exact tests, as appropriate. The relationship between the numeric pain scale and the visual analog scale is described using Pearson’s correlation coefficient. Results: Full data was provided from 94 patient surveys who completed surveys. The mean age was 61 years old, 56.4% were female, and 78.0% had metastatic cancer. Numerous cancer types were reported with gastrointestinal and lung cancers being the most common (30.1% and 23.7%, respectively). The mean NRS rating reported by patients was 5.9 and for the VAS 4.9. Sixty patients (63.8%) preferred the NRS, 32 (34.0%) preferred the VAS, and 2 (2.1%) reported no preference. Patients who preferred the NRS reported a higher NRS rating than patients who preferred the VAS (mean NRS of 6.3 compared to 5.2, p = 0.0409). VAS ratings were higher among patients who preferred the NRS but the difference was not statistically significant (mean rating of 5.2 vs. 4.4, p = 0.1894). There were no differences in patient characteristics between the two groups. There was a moderate association between patients’ NRS and VAS ratings. The Pearson correlation coefficient was 0.653 (p < 0.0001). Conclusions: Majority of patients of all ages and both genders prefer NRS. Future studies involving larger number of patients and adding a question about the reason of scale preference may provide better understanding for scale preference.